1. Field of the Invention
This invention relates to a power supply apparatus for television receiver set and television receiver set including the same and particularly to a power supply apparatus for television receiver set having satellite broadcasting or character broadcasting receiver and the television receiver set including the same.
2. Description of the Prior Art
Recently, some television receiver sets have contained a satellite broadcasting receiver or a character broadcasting receiver where each of these functions can be performed separately. In the television receiver set with such multi-function, individual operation among these functions is enabled by that one power supply apparatus is provided for one function because there is necessity of selectively operating these function for automatic recording by VTR, etc.
Hereinbelow will be described a prior art television receiver set including such a prior art power supply apparatus.
FIG. 9 is a block diagram of the prior art television receiver set having the prior art power supply apparatus. In FIG. 9, numeral 1 is an ac power supply input terminal; numeral 2 is a main switch for manually turning off all power supplies of the television receiver set; numeral 4 is a relay switch turned on/off in response to a control signal 3 from a microprocessor 100; numeral 6 is a relay switch which is turned on/off by a control signal 5 also sent from the microprocessor 100 for causing the television receiver set to enter an automatic recording condition wherein only the power supply for the television portion is turned off but a satellite broadcasting receiving circuit 24 is operated; numeral 7 is a line filter; numeral 8 is a rectifying circuit of a switching power supply 10 for the television portions, which rectifies and smooths an ac input voltage; numeral 9 is a rectifying circuit of a switching power supply 11 for the satellite broadcasting receiving circuit 24; numeral 12 is a remote control transformer for supplying a standby supply power for the microprocessor 100; numeral 13 is a rectifying circuit for the standby supply power; numeral 14 is a high voltage generation circuit having a flyback transformer (not shown); numeral 15 is a horizontal scanning circuit for horizontally scanning an electron beam; numeral 16 is a flyback pulse from the horizontal scanning circuit 15; numeral 17 is a supply voltage for the high voltage generation circuit 14 and the horizontal scanning circuit 15; numeral 18 is a vertical scanning circuit for vertically scanning the electron beam; numeral 19 is a supply voltage of the vertical scanning circuit 18; numeral 20 is a video signal processing circuit for converting an RF signal to an RGB signal to reproduce an image on a braun tube (not shown); numeral 21 is a supply voltage for the video signal processing circuit 20; numeral 22 is a voice signal output circuit comprising an amplifier, etc.; numeral 23 is a supply voltage of the voice signal output circuit 22; numeral 24 is the satellite broadcasting circuit for receiving a BS-IF signal; and numeral 25 are plural supply voltages for the satellite broadcasting receiving circuit 24. Moreover, supply voltages 17, 19, 21, and 23 are outputted to respective circuits from the switching power supply 10 and the supply voltage 25 is outputted from the switching power supply 11.
Hereinbelow will be described operation of power supply apparatus for the television receiver set having the above-mentioned structure.
At first, a condition that a picture image is displayed with all circuits being activated will be described. When the main switch 2 is closed, an ac voltage is supplied to the remote control transformer 12 from the ac power supply input 1, so that a standby supply power is generated in the rectifying circuit 13 of the secondary circuit. This power supplying starts operation of the microprocessor 100. If a user has selected watching of the television, the control signals 3 and 5 from the microprocessor 100 are so outputted to close both relay switches 4 and 6. The supply voltages are produced as follows:
The ac voltage from the ac input terminal 1 is passed through a line filter 7 and is rectified by the rectifying circuit 8 is supplied to the switching power supply 10. In the similar way, the supply voltage from the rectifying portion circuit 9 is supplied to the switching power supply 11. Then, both power supplies 10 and 11 start oscillation. The switching power supply 10 supplies the supply voltage 17, the supply voltage 19, the supply voltage 21, and the supply voltage 23 to the horizontal scanning circuit 15, the vertical scanning circuit 18, the video signal processing circuit 20, and the video signal output circuit 22 of secondary loads respectively as shown in FIG. 9. In the similar way, the switching power supply 11 supplies the supply voltage 25 to the satellite broadcasting receiving circuit 24. Thus, all circuits in the television for displaying image pictures and outputting voice sounds, so that the television receiver set is in a condition that the user can selected to which a programs of the ordinal television broadcasting or the satellite broadcasting is watched at will.
Hereinbelow will be described an automatic recording of a program of the satellite broadcasting which is carried out from the above-mentioned condition. That is, the following describes the operation of the television receiver set when the user desires to record a program by a video recorder (not shown) during his absence. This function is carried out under the condition that power supplying to the circuits of the television portion is stopped but only the satellite broadcasting receiving circuit is operated.
When the user gives the television a command for automatic recording by a remote controller (not shown) or by a keyboard on the front of the television (not shown), in response to the command, the microprocessor outputs the control signal 5 so as to open the relay switch 6. Then, the switching power supply 10 stops operation because the supply voltage is not supplied thereto through the line filter 7 and the rectifying circuit portion 8. Thus, picture images are not displayed on the screen of the television receiver set because each circuit as its secondary load does not operate. In this condition the main switch 2 and relay switch 4 remain close, so that the switching power supply 11 remains in operation and the satellite broadcasting receiving circuit 24 is in a condition of automatic recording wherein it maintains its operation with a given broadcasting selected.
However, in the above-mentioned structure, there is a drawback that the cost is high because an area for mounting elements is large since there are two sets of a line filter, a rectifying circuit, and a switching supply for both the television and the satellite broadcasting portion. In addition to this, there is also another drawback that a power supply for the microprocessor is separately necessary.